Discharge tube



March 15, 1949. G, DIE ER 2,464,562

DI S CHARGE TUBE Filed Nov. 22, 1946 IN VEN TOR.

GESINUS DIEMER AGENT Patented Mar. 15, 1949 DISCHARGE TUBE GesinusDiemer, Eindhoven, Netherlands, as-

signor to Hartford National Bank and Trust Company, Hartford, Conn, astrustee Application November 22, 1946, Serial No. 711,678 In theNetherlands October 6, 1945 Section 1, Public Law .690, August 8, 1946Patent expires October 6, 1965 3 Claims.

This invention relates to a discharge tube in which a stream ofelectrically charged particles is formed into a beam. Such dischargetubes are known for difierent purposes, in accordance with which thetubes are exhausted or furnished with a gasfilling- Therefore thecharged particles in these tubes are of a diiierent nature. Incathoderay tubes the charged particles are electrons, as in theso-called velocity-modulation tubes. Tubes in which the chargedparticles are not electrons are, for instance, cyclotrons and massspectrographs. In all these tubes the path of the beam requires to beinfluenced for various purposes. Thus, for instance, in cathode-raytubes it is necessary to draw an oscillogram or a television image, orto produce a current variation in a number of collecting electrodes. Invelocitymodulation tubes it may be desirable to cause the electrons totravel along a curved path to obtain a simpler positioning of theelectrode system. In cyclotrons and mass spectrographs curvature of thepath of the charged particles is vital for the operation of the tubei.'e. splitting of the ion beam into its various components.

In the present specification the expression stream of charged particleswhich is formed into a beam is not to be understood to mean that thepaths of the particles in the beam are all parallel, but that the anglebetween the paths is small. At any rate the formation into a beam issuch that there is a marked main direction of the stream of particles.

The paths of the charged particles can be infiuencedelectro-magnetically or electrostatically. A special manner ofinfluencing the path of the electron beam in cathode-ray tubeselectrostatically is obtained by means termed a cycling trac Thiscycling track comprises two curved coaxial cylindrical electrodes,provided on both sides of the electron beam, and serves to curve thebeam along a curved path through a given angle. Between the electrodesthere is set up a potential difference which is chosen in connectionwith the Velocity of the incoming electrons, the electrode distance andthe desired curvature of the path and of the electrodes, it beingassumed that an electron entering exactly midway between the electrodesof the cycle track has to follow a path extending midway between the twoelectrodes.

It appears that the cycle track construction is possessed of theparticular property that a beam entering parallel between the electrodesis iocussed. Regardless of the length of the cycle track a. focus isalways found at an angle of 2 rotation of 63.5 of the electron beam.Upon a rotation of 127 a parallel beam emerges gain in the paralleldirection.

The cycle track construction has also been described for tubes in whichthe charged particles are not electrons but, for instance, ions.

The particular properties of the cycle track construction resulting infocussing at 635 is a drawback since for several purposes focussing ofthe beam is required at a different angle of rotation. Another drawbackis due to the coaxial positioning of the electrodes of the cycle track,owing to which the distance between the electrodes is always the same.If, for instance, a diverging beam is caused to enter the cycle track,the beam, after a given angle of rotation, will have such a width thatsome of the electrons reach the electrodes, which is undesirable. Whenthe initial beam, before reaching the cycle track, is deflected by analternating voltage, the same drawbacks are experienced, since upon astrong deflection the beam is likely to be inter cepted by theelectrodes of the cycle track. The aforesaid drawbacks can be met bygiving the distance between the electrodes a large value. In this case,however, it is necessary, to set up a large potential diiTerence at theplates to ensure the desired path and to satisfy the condition that aparticle entering midway between the electrodes, continues to movemidway between the plates.

The aforesaid drawbacks of the cycle track construction are avoided in adischarge tube according to the invention, which comprises a number ofelectrodes by which a stream of charged particles is formed into a beamwhich, over part of the path travelled, is caused to follow a curvedpath by a number of curving electrodes placed on both sides of the beamand of which at least one is curved, these electrodes being positionedin such a manner that the distance between the electrodes on both sidesof the beam increases or decreases in the direction of motion of thebeam, and the line connecting the middles of these distance lines beingcurved in the same sense as the curving electrode exhibiting thestrongest curvature.

Since the electrodes diverge it can be provided that a diverging beam ora deflected beam is not intercepted by a curving electrode. Moreover,focussing may take place practically at any desired angle of curvature.

In a particular form of construction of a tube according to theinvention the curving electrode system comprises two curved electrodeseach of which consists of two interconnected curved parts, one of whichis the image of the other in a plane through the connecting points ofthe ,parts of each electrode.

Naturally the system according to the invenition may-be combined with anordinary cycle track or with a magnetic field of curvature. In the caseof deflection of the beam being desired, this may be effected by meansof separate electrodes or by dividing a curving electrode and bysupplying the deflecting voltage to part thereof. As has been said abovethis part may be the image of the remaining part of the curvingelectrode, but without being connected thereto.

In order that the invention may be more clearly understood and readilycarried into effect it may now be described more fully with reference tothe accompanying drawing, in which two forms of construction of acurving system of a tube according thereto are representeddiagrammatically.

Figure 1 is a cross-sectional view of ,ap plicant's novel electrodesystem;

Fig. 2 is a cross-sectional view of another of applicants novelelectrode system; and

Fig. 3 is a cross-sectional view, partially diagrammatic, of anembodiment of applicants invention comprising a cathode ray tube havinga fluorescent screen and including applicants novel electrodes.

In Figure 1 the I electron beam 1 is curved through an angle by curvingelectrodes 2 and 3 which are placed on both sides and diverge in thedirection of motion of the beam. Between the electrodes 2 and 3 is setup a given potential difference as a result of which the beam isfocussed at 4. The angle of curvature may be arbitrary owing to thedivergence of the electrodes.

In Figure 2 an electron beam l is curved through an angle e which in thepresent case amounts to 90. On both sides of the beam is provided acurved electrode 2 and 3 respectively. These electrodes consist of parts5, 6 and 1, 8 respectively, one of which is the image of the other inthe plane 1:.

The aforesaid curving systems may be used in various kinds of dischargetubes, for instance radio tubes, secondary-emission tubes, tubesinvolving deflection control e. g. television tubes, in cyclotrons, massspectrographs and so on.

In Fig. 3, there is shown somewhat diagrammatically a complete cathoderay tube comprising an envelope l having a cylindrical portion l6 and abulbous portion H. In the cylindrical portion. ['6 is an electron gunIt, a first anode [9, a second anode 20, and twopairs of deflectionplates 2|. In thebulbous portion I1 is a graphite coating 22 along thesides thereof with a lead 23 thereto and a fluorescent screen 24 on theface of said bulbous portion. A pair of electrodes 25, corresponding tothose illustrated in Fig. 2, are situated in the junction'between thecylindrical portion l6 and the bulbous portion ll of the envelope l5.Electrons leaving the gun and passing through the first and secondanodes are deflected by deflecting plates 2| and their path is curved bythe electrodes 25 in their passage therebetween through a angle, andfocused upon the screen 24 at a place thereof depending upon thedeflecting voltages on deflecting plates 2l'.

What I claim is:

1. A discharge tube comprising an envelope, and within the envelope,means to generate a beam of electrically charged particles, and means tocurve the path of said particles comprising two electrodes having activemetallic surfaces facing each other between which said beam is directed,said surfaces being curved in the same sense and being separated by adistance therebetween varying with the distance from the place of entryof said beam particles therebetween to the place of measurement of saidseparation distance.

2. A discharge tube comprising an envelope, and within the envelope,means to generate a beam of electrically charged particles and means tocurve the path of said particles comprising two electrodes each havingfirst and second xportions each having an active metallic surface, saidfirst portion surfaces facing each other and said second portionsurfaces facing each other, said facing portion surfaces havirg the beamdirected therebetween and being curved in the same sense and beingseparated by a distance therebetween varying with the distance from theplace of entry of said beam particles therebetween to the place ofmeasurement of said separation distance, said first and second portionsurfaces having a common plane of symmetry substantially normal to tl edirection of said beam at its intersection with said plane.

3. A discharge tube comprising an envelope,-

and within the envelope, means to generate a beam of electricallycharged particles and means to curve the path of said particlescomprising two electrodes each having electrically separate first andsecond portions each havi g an active metallic surface, said firstportion surfaces facing each other and said second portion surfacesfacing each other, said facing portion surfaces having the beam directedtherebetween and being curved in the same sense and being separated by adistance therebetween varying with the distance from the place of entryof said beam particles therebetween to the place of measurement of saidseparation distance, said first and second portion surfaces having acommon plane of symmetry substantially normal to the direction of saidbeam at its intersection with said plane.

GESINUS DIEMER.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 2,059,575 Gibson et a1 Nov. 3,1936 2,138,928 Klemperer Dec. 6, 1938 2,289,770 Fremlin July 14, 194-2

